JP2013221605A - Ball screw device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball screw device that can facilitate mounting of a dust-proof member regardless of the thickness of a nut.SOLUTION: A ball screw device includes a screw shaft 10 and a nut 20 which is relative movably screwed to the screw shaft 10 through balls 30, and an engagement groove 22 is formed in a circumferential direction on an inner circumferential surface 20a of the nut 20 with a predetermined distance from the edge in an axial direction. The nut 20 is fitted with a cylindrical dust-proof member 40 for sealing the space between the screw shaft 10 and the nut 20. An outer circumferential surface 40a of the dust-proof member 40 is provided with a falling-off prevention engagement piece 41 that can engage with the engagement groove 22 of the nut 20, and a rotation prevention engagement piece 42 for preventing the rotation of the dust-proof member 40 fitted to the nut 20.

Description

  The present invention relates to a ball screw device.

A ball screw device used as a mechanical element that converts rotational motion into linear motion generally has a screw shaft and a cylindrical nut provided on the outer periphery of the screw shaft. A plurality of balls are incorporated between the formed spiral ball rolling groove and the spiral ball rolling groove formed on the inner peripheral surface of the nut.
In such a ball screw device, if a foreign matter such as dust adhering to the surface of the screw shaft enters the inside of the nut, the smooth rolling motion of the ball is hindered. Often attached to the end face of

  An example of a ball screw device provided with such a dustproof member is described in Patent Document 1. This ball screw device has a structure in which a tapped hole penetrating in the radial direction is provided on the outer peripheral surface of the nut, and a fastening screw is inserted into the tapped hole to fix the dustproof member in the rotational direction and the axial direction. .

Here, as shown to Fig.5 (a)-(f), in the prior art described in patent document 1, when attaching a dust-proof member to a nut, it passes through the following attachment procedures (1)-(6).
(1) As shown in FIG. 5A, the dustproof member 140 is inserted into the dustproof member insertion hole 122 provided on the end surface of the nut 120. Here, the nut 120 is provided with a tap hole 121 penetrating the outer peripheral surface 120a and the inner peripheral surface 120b.
(2) As shown in FIG. 5 (b), the drill 200 with the stopper 210 attached to the tip is inserted into the tap hole 121, and the drill 200 is used to reach a predetermined depth from the outer peripheral surface of the dustproof member 140. Then, the mounting hole 141 is dug.

(3) As shown in FIG. 5C, the drill 200 is extracted, and the dustproof member 140 is further removed from the dustproof member insertion hole 122.
(4) As shown in FIG. 5 (d), air blow or suction is applied to the dust-proof member 140 removed from the nut 120 to remove scraps.
(5) As shown in FIG. 5 (e), the dustproof member 140 is attached to the end surface of the nut 120 again, the fastening screw 125 is inserted into the tap hole 121, and the dustproof member 140 is fixed to the nut 120.
(6) As shown in FIG. 5 (f), using a caliper (or a dedicated gauge) 400, it is confirmed that the fastening screw 125 is inserted to the dustproof member 140 to a predetermined depth.

JP 2002-349664 A

However, in the conventional ball screw device described in Patent Document 1, since the screw hole 121 is provided in the nut 120, the labor required for the processing may reduce the yield. In particular, in forming the screw hole 121, when the thickness of the nut 120 is large, it is necessary to process not only the tapped hole processed with the female screw groove but also the drill hole. There was room for improvement because of variations in In particular, in such a ball screw device that requires processing of the screw hole 121, when the processing timing of the screw hole 121 is not after the lubricant is sealed in the ball screw device, that is, the nut 120 is provided with an oil supply hole or a lubricant. When the sealing hole is not provided, it is necessary to apply the lubricant to the outer surface before inserting the dustproof member 140. In such a case, the lubricant may be applied to, sealed in, or attached to the tapped hole provided in the nut 120, and after fixing the dustproof member 140 with the fastening screw 125, or mounting the ball screw device on the machine base, Fastening screws may loosen during operation. As a result, the dust-proof member 140 is detached from the end surface of the nut 120, and foreign matter, dust, and cutting residue are mixed in the nut 120. As a result, the ball screw device may malfunction and there is room for improvement. It was.
Accordingly, the present invention has been made paying attention to the above-mentioned problems, and an object of the present invention is to provide a ball screw device capable of easily mounting a dustproof member regardless of the thickness of the nut. .

The invention according to claim 1 for achieving the above object includes: a screw shaft; a nut provided on an outer periphery of the screw shaft; a spiral ball rolling groove formed on an outer peripheral surface of the screw shaft; A plurality of balls provided between a spiral ball rolling groove formed on the inner peripheral surface of the nut,
On the inner peripheral surface of the nut, an engagement groove is formed in the circumferential direction with a predetermined distance from the axial end,
A cylindrical dustproof member that seals a gap between the screw shaft and the nut is attached to the nut,
An outer peripheral surface of the dust-proof member is elastically deformed and engaged with the engagement groove to prevent the dust-proof member from coming off in the axial direction. An anti-rotation engagement piece that engages with the peripheral surface and prevents rotation of the dust-proof member attached to the nut is provided side by side in the circumferential direction.

According to a second aspect of the present invention, in the ball screw device according to the first aspect of the present invention, a plurality of at least one of the slip-off preventing engagement pieces and the rotation-preventing engagement pieces are provided.
According to a third aspect of the present invention, in the ball screw device according to the first or second aspect, at least one of the removal prevention engagement pieces and the rotation prevention engagement pieces is provided in a plurality of different lengths. It is characterized by that.

According to a fourth aspect of the present invention, in the ball screw device according to any one of the first to third aspects, at least one of the removal prevention engagement piece and the rotation prevention engagement piece is provided in a circumferential direction of the dustproof member. It is characterized by being provided at equal intervals.
Moreover, the invention which concerns on Claim 5 WHEREIN: In the ball screw apparatus in any one of Claims 1-4, the some notch part was provided in the outer peripheral surface of the said dust-proof member along with the circumferential direction. It is a feature.

  ADVANTAGE OF THE INVENTION According to this invention, the ball screw apparatus which can make easy mounting | wearing of a dust-proof member irrespective of the thickness of a nut can be provided.

It is sectional drawing which follows the axial direction which shows the structure in one Embodiment of the ball screw apparatus which concerns on this invention. It is a figure which shows the structure of the dust-proof member in one Embodiment of the ball screw apparatus which concerns on this invention, (a) is a right view, (b) is a front view, (c) is 2c-2c sectional surface of (b). , (D) is a rear view. It is a figure which shows the attachment procedure of the dustproof member in one Embodiment of the ball screw apparatus which concerns on this invention, (a) is sectional drawing in alignment with the axial direction before attaching a dustproof member to a nut, (b) is a dustproof member. It is sectional drawing which follows the axial direction after mounting | wearing with a nut. It is a figure which shows the structure of the dustproof member in other embodiment of the ball screw apparatus which concerns on this invention, (a) is a right view, (b) is a front view, (c) is 4c-4c cross section of (b). Surface (d) is a rear view. It is a figure which shows the attachment procedure of the dust-proof member in the conventional ball screw apparatus.

Embodiments of a ball screw device according to the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view along the axial direction showing the configuration of an embodiment of a ball screw device according to the present invention. FIG. 2 is a diagram showing the configuration of the dust-proof member in one embodiment of the ball screw device according to the present invention, where (a) is a right side view, (b) is a front view, and (c) is (b). 2c-2c cross-sectional surface, (d) is a rear view.

As shown in FIG. 1, the ball screw device 1 of the present embodiment includes a screw shaft 10, nuts 20, and a plurality of balls 30.
The screw shaft 10 has a spiral ball rolling groove 11 on the outer peripheral surface, and a spiral ball rolling groove 21 is formed on the inner peripheral surface of the nut 20 provided on the outer periphery of the screw shaft 10. It is formed with the same lead as the moving groove 11.
The ball rolling grooves 11 and 21 are opposed to each other, and the plurality of balls 30 provided between the ball rolling grooves 11 and 21 are rotated by the relative rotation of the screw shaft 10 with respect to the nut 20. It rolls between the grooves 11 and 21. Then, the ball 30 that has rolled between the ball rolling grooves 11 and 21 passes through a ball return tube (not shown) assembled to the nut 20 and is returned to its original position. Between these ball rolling grooves 11 and 21 and the ball return tube form a rolling path.

[Engagement groove]
Further, a circular engagement groove 22 is provided in the circumferential direction at a predetermined distance from the end portion in the axial direction on the inner peripheral surface 20a of the nut 20. One engagement groove 22 is preferably provided from each end of the nut 20, and a plurality of engagement grooves 22 are provided as necessary. Here, the said predetermined distance is set based on the dimension of the axial direction of the dustproof member 40 mentioned later.

<Dustproof material>
As shown in FIGS. 2A to 2D, the dustproof member 40 has a cylindrical shape. On the outer peripheral surface 40a of the dust-proof member 40, a slip-off preventing engagement piece 41 and a rotation-preventing engagement piece 42 are provided side by side in the circumferential direction. Hereinafter, the removal preventing engagement piece 41 and the rotation preventing engagement piece 42 may be simply referred to as engagement pieces 41, 42.

[Engagement prevention piece]
Prevention engaging pieces 41 missing, the axial length (length along the penetrating direction of the dustproof member 40) d ₄₂ is the axial length d ₂₂ below the protrusion of the engagement groove 22 (FIGS. 1 and FIG. 2 (c)).
When the dust-proof member 40 is attached to the nut 20 while the outer peripheral surface 40a of the dust-proof member 40 and the inner peripheral surface 20a of the nut 20 are in sliding contact with each other, the slip-off preventing engagement piece 41 is elastically deformed to form the engagement groove 22. Engagement prevents the dustproof member 40 from coming off the nut 20 in the axial direction.

[Anti-rotation engagement piece]
On the other hand, the anti-rotation engaging piece 42 is its axial length (length along the penetrating direction of the dustproof member 40) d ₄₂ is longer projections than the axial length d ₂₂ of the engagement groove 22 ( 1 and FIG. 2 (c)).
The anti-rotation engaging piece 42 is elastically deformed when the dust-proof member 40 is attached in the nut 20 while the outer peripheral surface 40a of the dust-proof member 40 and the inner peripheral surface 20a of the nut 20 are slidably contacted, and the inner periphery of the nut 20 Engage with the surface 20 a to prevent rotation of the dustproof member 40 attached to the nut 20.

[Installation mode of engagement piece]
Here, the slip-off preventing engagement piece 41 and the rotation-preventing engagement piece 42 may be provided on the outer peripheral surface 40a of the dust-proof member 40 one by one. It is preferable that at least one of the plurality is provided, and it is more preferable that each of the plurality is provided. For example, as shown in FIGS. 2 (b) and 2 (c), two removal prevention engagement pieces 41 </ b> A and 41 </ b> B and two rotation prevention engagement pieces 42 </ b> A and 42 </ b> B are disposed on the outer peripheral surface 40 a of the dust-proof member 40. In this case, “the length of the slip prevention engagement piece 41A” <“the length of the slip prevention engagement piece 41B” <“the length of the rotation prevention engagement piece 42A” <“the length of the rotation prevention engagement piece 42B”. It is preferable that it is provided so as to become.

Further, when the two anti-detachment engagement pieces 41A and 41B and the two anti-rotation engagement pieces 42A and 42B are disposed on the outer peripheral surface 40a of the dust-proof member 40, the “prevention prevention engagement pieces 41A” and “ It is more preferable that the anti-detachment engagement piece 41B, the anti-rotation engagement piece 42A, and the anti-rotation engagement piece 42B are provided periodically in order of increasing length.
In addition, the engagement pieces 41 and 42 are preferably arranged on the outer peripheral surface 40a of the dustproof member 40 at equal intervals. For example, it is preferable that the engagement pieces 41, 42 are arranged in plural numbers (2 equal distribution, 3 equal distribution, 4 equal distribution, 5 equal distribution, 6 equal distribution, etc.) on the outer peripheral surface 40 a of the dustproof member 40.

  In addition, it is preferable that the engagement pieces 41 and 42 are each integrally formed of an elastic material together with the dustproof member 40. Further, the radial thickness on the end face side of the dust-proof member 40 where the engagement pieces 41 and 42 are not provided is made larger than the radial thickness of the engagement pieces 41 and 42. This is because when the engaging pieces 41 and 42 are elastically deformed, the bending moment on the end surface side of the dustproof member 40 where the engaging pieces 41 and 42 are not provided is larger than the bending moment in the engaging pieces 41 and 42. This is because the cross-sectional secondary moment of the portion is increased because of the large size.

<Attaching the dustproof member>
Next, a procedure for attaching the dustproof member 40 will be described with reference to FIG.
FIG. 3 is a view showing a procedure for attaching a dustproof member in an embodiment of the ball screw device according to the present invention, wherein (a) is a cross-sectional view along the axial direction before the dustproof member is attached to a nut, and (b). FIG. 5 is a cross-sectional view along the axial direction after the dust-proof member is attached to the nut.

  As shown in FIGS. 3A and 3B, the dust-proof member 40 is fitted into the nut 20 while the outer peripheral surface 40 a and the inner peripheral surface 20 a of the nut 20 are in contact with each other. At this time, the anti-detachment engagement piece 41 is engaged with the engagement groove 22 while being elastically deformed, whereby the dustproof member 40 is fixed to the nut 20 and the dustproof member 40 is detached from the nut 20 in the axial direction. Can be prevented. At the same time, the anti-rotation engagement piece 42 is not engaged with the engagement groove 22 while being elastically deformed, and is biased to the inner peripheral surface 20a of the nut 20. As described above, the anti-rotation engagement piece 42 biases the inner peripheral surface 20 a of the nut 20, whereby the dust-proof member 40 can be prevented from rotating with respect to the nut 20. In this way, the dustproof member 40 attached to the nut 20 seals the gap between the screw shaft 10 and the nut 20. By providing a plurality of the engagement pieces 41 and 42, it is possible to further improve the prevention of the dustproof member 40 from coming off or preventing the rotation. Here, by providing the anti-detachment engagement piece 41 and the rotation-prevention engagement piece 42 on the dust-proof member 40, the effect of absorbing “variation during processing”, “deformation after heat treatment” and the like of the engagement groove 22 is obtained. is there.

  In the ball screw device 1 according to the present embodiment, two disconnection prevention engagement pieces 41 and two rotation prevention engagement pieces 42 are set (see FIG. 2B). In addition, it is only necessary that at least one anti-rotation engagement piece 42 is provided on the dust-proof member 40. The engagement pieces 41, 42 are not defined based on the width of the engagement groove 22 provided in the nut 20, but are determined based on whether or not the engagement pieces 22 are engaged. Or “rotation preventing engagement piece 42” may be determined as a result. Specifically, when there are a plurality of nuts 20 having different widths of the engagement groove 22 and the dustproof member 40 is installed in each of the nuts 20, the engagement piece engaged with the engagement groove 22 is “a drop prevention engagement piece 41. , And the engagement piece that has not engaged with the engagement groove 22 functions as the “rotation prevention engagement piece 42”. For example, if a plurality of sets of engagement pieces 41 and 42 are provided on the dust-proof member 40 over four stages, the three engagement pieces engaged with the engagement groove 22 are “disengagement prevention engagement pieces 41”. The remaining one engaging piece that does not engage with the engaging groove 22 functions as the “rotation preventing engaging piece 42”. On the other hand, one engagement piece engaged with the engagement groove 22 functions as the “detachment prevention engagement piece 41”, and the remaining three engagement pieces not engaged with the engagement groove 22 are “rotation prevention engagement pieces”. 42 ".

  In addition, as compared with “an aspect in which the anti-detachment engagement pieces 41 and the anti-rotation engagement pieces 42 are randomly provided”, “the engagement pieces 41 and 42 having different lengths are periodically (in order of length) ( For example, 6 sets of 4 each; see FIG. 2B) is preferable because the balance when the dustproof member 40 is mounted is good and the manufacturing cost can be reduced.

(Other embodiments)
Next, another embodiment of the ball screw device according to the present invention will be described with reference to the drawings. In addition, since this embodiment differs only in the structure of the circulation member from the above-mentioned embodiment, description is abbreviate | omitted about the same structure which attached | subjected the same code | symbol as the above-mentioned embodiment. FIG. 4 is a diagram showing the configuration of a dustproof member in another embodiment of the ball screw device according to the present invention, where (a) is a right side view, (b) is a front view, and (c) is a diagram of (b). 4c-4c cross section, (d) is a rear view.

As shown in FIGS. 4A to 4D, in the ball screw device 1 of the present embodiment, a plurality of cutout portions 43 are provided on the outer peripheral surface 40a of the dustproof member 40 side by side in the circumferential direction. These cutout portions 43 are preferably provided between the engagement pieces 41 and 42. 4A to 4D, the notch 43 is provided on the opposite surface side of the dust-proof member 40 facing the nut 20 to be mounted, but may be provided on the opposite surface. .
Thus, the engagement pieces 41 and 42 can be independently moved by providing the plurality of notches 43 in the circumferential direction on the outer peripheral surface 40a of the dust-proof member 40. Therefore, the prevention of the dustproof member 40 from coming off from the nut 20 and the prevention of rotation are further improved.

As described above, since the ball screw device 1 according to the present embodiment can attach and remove the dust-proof member 40 to and from the nut 20 by elastic deformation, it is easy to attach the dust-proof member regardless of the thickness of the nut 20. Can be.
Further, by providing engagement pieces 41 and 42 of different lengths on the outer peripheral surface 40 a of the dust-proof member 40, the nut 20 can be prevented from coming off and prevented from rotating, and the dust-proof member 40 can be securely fixed to the nut 20.
The ball screw device according to the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Ball screw apparatus 10 Screw shaft 11 Ball rolling groove 20 Nut 21 Ball rolling groove 22 Engaging groove 30 Ball 40 Dust-proof member 41 Anti-detachment engagement piece 42 Anti-rotation engagement piece 43 Notch

Claims (5)

A screw shaft, a nut provided on the outer periphery of the screw shaft, a spiral ball rolling groove formed on the outer peripheral surface of the screw shaft, and a spiral ball rolling formed on the inner peripheral surface of the nut A plurality of balls provided between the grooves,
On the inner peripheral surface of the nut, an engagement groove is formed in the circumferential direction with a predetermined distance from the axial end.
A cylindrical dustproof member that seals a gap between the screw shaft and the nut is attached to the nut,
An outer peripheral surface of the dust-proof member is elastically deformed to engage with the engagement groove and prevent the dust-proof member from coming off in the axial direction. A ball screw device, characterized in that a rotation prevention engagement piece that engages with a circumferential surface and prevents rotation of the dustproof member attached to the nut is provided side by side in the circumferential direction.   The ball screw device according to claim 1, wherein a plurality of at least one of the slip-off preventing engagement piece and the rotation-preventing engagement piece is provided.   3. The ball screw device according to claim 1, wherein a plurality of at least one of the slip-off prevention engagement pieces and the rotation prevention engagement pieces are provided with different lengths.   The ball screw device according to any one of claims 1 to 3, wherein at least one of the slip-off prevention engagement piece and the rotation prevention engagement piece is provided at equal intervals in the circumferential direction of the dust-proof member.   The ball screw device according to any one of claims 1 to 4, wherein a plurality of cutout portions are provided side by side in the circumferential direction on the outer peripheral surface of the dustproof member.

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